But the iPhone 6 is still a huge hit, and Apple’s stock price has responded accordingly. It has jumped more than 30% since the smartphone went on sale last year.

On the other hand, Apple’s stock has stayed relatively flat since the company began shipping the Apple Watch in late April. This is Apple’s first new product segment in five years, but its reception remains murky.

Apple won’t disclose sales figures for the smartwatch. That said, the “other” product category that includes the device saw revenue of $2.6 billion for the June quarter, compared with about $3.6 billion expected by analysts. That appeared to be a notable shortfall, at least from limited data at hand.

The iPhone accounts for more than 60% of Apple’s total revenue versus a nominal contribution from the Apple Watch, so investors are wise to give the former much more weight. But this doesn’t always work in Apple’s favor.

The company’s smartphone sales for the June period barely exceeded analysts’ estimates after beating targets by an average of 13% over the past three quarters, according to FactSet. This, along with a conservative forecast for the September quarter, weighed on Apple’s stock Tuesday, sending the shares tumbling after hours.

That might seem nitpicky considering the iPhone’s track record, but it also points to the challenge: Apple has to diversify its story. The iPhone faces tough comparisons in the coming fiscal year. The iPad  Apple’s second largest product  continues to see its sales decline. And the company’s limited disclosures about its first smartwatch remain puzzling, and not something that can be reliably valued.

One big plus for Apple is that its stock remains a relative bargain. It trades at a 20% discount to the S&P 500 based on multiples of forward earnings. That compares with a 13% discount at this time last year.

That should help temper the fallout from the quarter. But it also shows Apple needs to reach beyond the iPhone.